1. Field of the Invention
The present invention relates generally to draft implements of the type having an input driveline connected to and powered by a power takeoff shaft of the towing vehicle and, more particularly, is concerned with improved means for supporting the implement driveline so as to accommodate bottoming out of a telescoping assembly in the driveline during sharp turns of the tractor relative to the implement.
2. Description of the Prior Art
Balers, mower-conditioners and other agricultural pull-type implements commonly have a tongue which is adapted to be articulately connected at its hitch end to the drawbar of a tractor. Also, such implements commonly have an input driveline adapted to be connected to the power takeoff shaft of the tractor for transmitting rotary power to the operating components of the implement. The implement driveline frequently includes a forward telescoping drive assembly located above the tongue hitch end and the tractor drawbar which is articulately coupled to the tractor power takeoff shaft by a forward universal joint located forwardly of the connection of the hitch end to the drawbar and articulately coupled to the remainder of the driveline by a rear universal joint located rearwardly of the connection of the hitch end to the drawbar.
During turns of the tractor relative to the implement, if the angle of articulation at the forward universal joint is substantially different than the angle of articulation at the rear universal joint, the rotary speed of the implement driveline will fluctuate relative to the tractor PTO shaft rotary speed. The resulting speed variations in the implement driveline are, of course, highly undesirable and produce wear and excessive vibration in the implement driveline.
Therefore, it is desirable to keep the forward and rear universal joint angles as nearly equal as possible during articulation of the tractor relative to the implement. This makes it necessary to make the distance from the rear universal joint to the point of connection between the implement tongue and the tractor drawbar the same as the distance from the forward universal joint to such connection point. It is a standard in the tractor industry, for instance, at 540 rpm power takeoff speeds, that the forward universal joint be approximately 11 11/16 inches from the tongue hitch/drawbar connection point. Thus, when the implement is designed to provide this same distance between the rear universal joint and the tongue hitch/drawbar connection point, the result is that the telescoping drive assembly intercoupled between the forward and rear universal joints has a relatively short length. Since the telescoping parts of the assembly must be capable of extending and retracting as the tractor turns or articulates relative to the implement during field operation and must be long enough so as not to separate during field operation, the assembly will generally bottom out at tractor/implement turning angles which are smaller, or less sharp, than will be required for efficient field operation of the implement.